1. Field of the Invention
The present invention relates to a headphone, and more particularly, to a headphone that has stable air exhaust and outputs high quality audio.
2. Description of Related Art
Headphones generally have speakers inside. The speakers generate sound waves by vibrating membranes therein. Various structures of headphones have been designed to make the audio coming out of the headphones smoother and of higher quality. For example, it is a common practice to form air holes on headphones.
Referring to FIG. 5, U.S. Pat. No. 4,058,688, discloses a headphone with a speaker unit 90. Multiple holes 92 are formed on a front cover 91 of the speaker unit 90 for a speaker 93 to transmit sound therethrough. In other words, the airflows generated by the speaker 93 flow through the holes 92. To make the sound smoother, multiple holes 95 are formed on a back cover 94 of the speaker unit 90.
However, because the holes 95 are formed on the back cover 94, a desired aesthetic design of the back cover 94 may not be achievable. In addition, to get a smooth and quality sound, the quantity of the holes 95 has to reach a certain number. Otherwise, the air exhaust will be affected and the sound quality will be degraded. With limited area of the back cover 94, it is a challenge to maintain the quality of the sound while controlling the manufacturing cost.